this sounds like a great question! :D my son was sleeping much the same at 15 months. i nursed him until he weaned himself at 19 months, and he slept with us starting at like 4 or 5, until around 7-730. about 20 months we noticed that he wanted to sleep flopped on top of one of our pillows, to the point where one night we put one in his crib and he flopped right down on it and he went right to sleep! so try that - give your daughter a nice full sized pillow.
our sons crib is right in our room, and i dont plan on changing that. i like the fact that hes right there if something happens... i know its probably unlikely, and its just some crazy "what if" story, but if our furnace starts on fire, our sons room is on the other side of it from our room... and i just feel safer knowing that i would just have to pick him up and head out the window instead of having to cross "through the fire" to get to him...
many parents put their kids on matresses on their bedroom floors, something that the sears famiy of doctors also suggests! www.askdrsears.com
this sounds like a fine solution, however, try the pillow thing in her crib. she might like that :D but take it easy, the more gentle you can make this for her, the easier it will be for her to mature and grow. you sound like a mom who is well in tune with her childs needs and thats a good thing! :D dont let anyone tell you otherwise. you know your instincts are right, and not the advice of someone else. i once heard someone say they wished their bedroom was just a room of matresses! :D that way the whole family could sleep right on the floor! :P
anyway, good luck, and congrats on the new one coming, and just keeping listening to your instincts! :D